This invention relates to the fields of tempo and beat detection where the tempo and the beat of an input audio signal is automatically detected. Given an audio signal, e.g. a .wave or .aiff file on a computer, or a MIDI files (e.g., as recorded on computer from a keyboard), the task is to determine the tempo of the music (the average time in seconds between two consecutive beats) and the location of the downbeat (the starting beat).
Various techniques have been described for detecting tempo. In particular, in a paper by E. D. Scheirer, entitled "Tempo and Bean analysis of acoustic musical signals", J. Acoust. Soc. Am. 103 (1), January 1988, pages 588-601, a technique utilizing a bank or resonators to phase-lock with the beat and determine the tempo of the music is described. A paper by J. Brown entitled "Determination of the meter of musical scores by autocorrelation", J. Acoust. Soc. Am. 94(4), October 1993, pages 1953-1957, describes a technique where the autocorrellation of the energy curve of a musical signal is calculated to determine tempo.
Research continues to develop effective, computationally efficient methods of determining tempo and locating beats.